LiveActive security incident?Get immediate response
CVE Record

CVE-2020-25817: SilverStripe through 4.6.0-rc1 has an XXE Vulnerability in CSSContentParser.

SilverStripe through 4.6.0-rc1 has an XXE Vulnerability in CSSContentParser. A developer utility meant for parsing HTML within unit tests can be vulnerable to XML External Entity (XXE) attacks. When this developer utility is misused for purposes involving external or user submitted data in custom project code, it can lead to vulnerabilities such as XSS on HTML output rendered through this custom code. This is now mitigated by disabling external entities during parsing. (The correct CVE ID year is 2020 [CVE-2020-25817, not CVE-2021-25817]).

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This issue affects SilverStripe through 4.6.0-rc1 when a developer test utility, CSSContentParser, is reused against external or user-submitted data. That misuse can allow unsafe XML entity handling and may result in downstream issues such as XSS in custom-rendered HTML.

Executive priority

Prioritize review if the organization runs custom SilverStripe code or accepts rich user-submitted content. This is not presented as a broad default exploit, but misuse in production code can create meaningful web application risk.

Technical view

CSSContentParser, described as a developer utility for parsing HTML in unit tests, was vulnerable to XXE behavior before external entities were disabled during parsing. Exposure depends on custom project code using this utility with untrusted input and rendering affected HTML output.

Likely exposure

Most risk is in custom SilverStripe applications that call CSSContentParser on external or user-submitted content. Standard deployments without that misuse may have limited exposure, but the bundle does not provide complete product or version metadata beyond SilverStripe through 4.6.0-rc1.

Exploitation context

The bundle does not cite active exploitation, and KEV is false. Practical impact appears conditional: an attacker would need a reachable custom code path that feeds untrusted content into the vulnerable parser and uses the resulting output unsafely.

Researcher notes

The CVE record emphasizes misuse of a unit-test developer utility rather than a normal public endpoint. The provided data lacks CVSS, CWE, CPE, and precise fixed version details, so validation should focus on code usage and vendor advisory confirmation.

Mitigation direction

  • Upgrade to a SilverStripe release containing the external-entity parsing mitigation.
  • Check SilverStripe advisory guidance for exact supported fixed versions.
  • Remove CSSContentParser use from user-facing or external-data paths.
  • Ensure XML parsing disables external entity resolution where applicable.
  • Review custom HTML rendering for escaping and XSS controls.

Validation and detection

  • Inventory SilverStripe versions and flag deployments through 4.6.0-rc1.
  • Search custom code for CSSContentParser usage.
  • Confirm whether any usage processes external or user-submitted data.
  • Review rendered HTML paths fed by parser output.
  • Verify the installed version includes external-entity disabling during parsing.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2020-25817 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.